In recent years, a radar apparatus which detects an object around a vehicle is provided in the vehicle, so as to detect another vehicle ahead of the vehicle, a walking person, or the like. Many of such radar apparatuses employ a method in which an ultrasonic wave or an electromagnetic wave is radiated to an object and the reflected wave from the object is received whereby the position of the object is detected.
For example, Patent Literature 1 discloses a radar apparatus employing a so-called phase monopulse technique which detects the position of an object, based on the phase difference between reflected waves received by a plurality of antennas. The radar apparatus of Patent Literature 1 includes: a reception antenna including array antennas composed of a plurality of device antennas arrayed in the horizontal direction; and a signal processing section which electrically scans the antenna pattern of the reception antenna in the horizontal direction, thereby recognizing an object present in a horizontal direction within a predetermined range of angles, from reception signals received by the reception antenna. In addition, in the radar apparatus, at least some of the device antennas are placed being displaced from each other in the vertical direction. The signal processing section detects, by monopulse technique, the position of an object with respect to the vertical direction by using reception signals received by the device antennas displaced from each other in the vertical direction.